The subject of the present invention is a braking band for a self-ventilated disk-brake disk.
A known type of disk-brake disk with a self-ventilated braking band comprises basically a support bell for connection, for example, to a vehicle wheel hub. The braking band, which cooperates with the calipers in order to exert the braking force on the vehicle, is connected to the bell by means of a connector. The braking band typically comprises at least two parallel plates separated by connecting elements which fix them together. The space between the plates forms an air duct. By virtue of the circulation of air between the plates, the disk is cooled, both on the outer sides of the braking band, as for a solid disk, and also on the inner sides of the braking band.
As is known, during the braking operation, the disks may be subject to vibrations which translate into annoying squeals. A known approach for preventing this noise due to the vibrations of the brake disk consists in the formation of grooves which are produced in the braking surfaces of the braking band by turning and extend throughout the thickness of the plates. If the stiffness of the brake disk is thus changed locally, its dynamic characteristics are changed so as to move the natural frequencies of the brake disk away from the frequencies which are excited during braking.
However, these grooves in the braking surfaces of the braking band lead to technological and structural disadvantages which relate to the acoustic behaviour, to the production, and also to the mechanical behaviour of the disk, as well as to the type of pad required by a partially interrupted braking surface.
In fact, the production of a surface with a plurality of grooves produced by turning requires considerable expenditure in terms of time and cost.
When the aforementioned grooves which extend as far as the space between the two plates are produced by machining, starting from the outer surface, sharp edges are formed in the connecting elements between the plates and may introduce dangerous notching effects which in turn constitute stress raisers. Moreover, the connecting elements are weakened because of the inevitable removal of material from their ends when, during the machining of the through-grooves, starting from the outside and continuing towards the space between the plates, breakthrough takes place into the space.